Robert Carlyle stars as the UK prime minister, who's forced to scramble an emergency committee when a solar storm threatens to strike.

With the nation in the full grip of the crisis and experiencing the worst blackout in the history of the UK, Sutherland and his team are forced to work around the clock to restore power. Meanwhile, there is danger as Anna reconnects with Edin.

As the country continues to face dark days, the PM, Anna, Fraser and their teams pay a visit to the worst affected area. Meanwhile, Archie's rhetoric threatens to cause more problems for everyone.

As questions are asked about Sutherland's knowledge of his daughter's involvement in her friend's death, Anna seeks the help of Eleanor in handling the new revelations about Edin. Meanwhile, a new threat rears its head as public sentiment grows more turbulent.

As the nation slides into anarchy, Sutherland considers extreme measures to keep control of the country. Elsewhere, Rachel faces tough questions about Ellie.

As his personal life implodes, Sutherland is forced to fight for his political career. Meanwhile, anarchy comes to the streets as riots rock the nation.